Bisbenzoeyclobutene compounds are known and exemplified in U.S. Pat. No. 4,540,763. One such compound: ##STR2## can be made by the reaction of bromobenzocyclobutene with m-divinylbenzene to produce a solid product having a melting point of 150.degree.-152.degree. C. The monomers disclosed in U.S. Pat. No. 4,540,763 are useful in preparing thermoset and thermoplastic polymeric compositions. While these compositions exhibit excellent thermal stability and chemical resistance and have uses as films, coatings, adhesives, fiber-reinforced plastics, composites, structural laminates and other engineering applications, they have the undesirable feature in that they are solids at room temperature and require processing prior to polymerization processes. They must be dissolved in a solvent, processed from the melt of the monomer or subjected to B-staging (partial conversion to higher molecular weight) to yield an amorphous lower melting solid that has increased viscosity necessary for processing.
Liquid bisbenzocyclobutene monomers bridged by a polyorganosiloxane group are disclosed in U.S. Pat. No. 4,812,588. These monomers can be prepared by reacting a bromobenzocyclobutene with the desired organopolysiloxane bridging group and are particularly useful for electronic applications. Although these monomers are liquid as isomeric mixtures, they are not liquids in their pure form.
It would be useful to have bisarylcyclobutene monomers which are liquid at room temperature and produce thermally stable polymers with good physical and mechanical properties.
It would also be desirable to have liquid bisarylcyclobutene monomers having a variety of bridging groups for use as homopolymers, comonomers in polymeric compositions or reactive diluents with other monomers. It would also be desirable to have polymeric compositions of these monomers for use in advanced composites and microelectronics.